Originally Posted by
paperwastage
that's what @
LondonElite was alluding to - ability to enter Japan on the 1st ticket (UA will check for that. doesn't matter if you have separate connecting ticket, UA checks if you are admissible to the 1st country Japan and gets fined/costs of flying passenger out of japan, if passenger cannot enter Japan and gets deported)
Exactly. OP’s contract with UA is to get him to Japan. If he is not permitted to enter Japan, he won’t be getting on the plane in the first place.